Pulverizing mill



2 Sheets-Sheet 1 0. DA C. SCHMIDT 'PULVERIZING MILL Filed Nov. 29, 1932 Dec. 5, 1933;

0/72 02/ 605/0, Jafimi INVENTOR.

ATTORNEY.

I. Illll Ill-Ill. lllll 2 Sheets-Shet 2 0. DA C. SCHMIDT PULVERIZING MILL Filed Nov. 9, 19 2 Dec. 5, 1933.

INVENTORQ Patented Dec. 5, 1933 UNITED STATES PATENT OFFICE Application November 29, 1932 Serial No. 644,895

8 Claims.

This invention relates to improvements in pulverizing mills, especially designed for production of bronze, copper, aluminum and other metallic powder.

An object of the present invention is to generally improve pulverizing mills of the type embodying an internally grooved grinding ring and a rotatable carrier having radially movable grinding elements arranged to travel in the groove of said grinding ring.

-A more specific object of the invention is to provide a pulverizing mill of the above type in which, during each revolution of the carrier, each grinding element is forcibly projected outwardly against the grinding ring to pound and reduce the metal, in which the grinding element is then forcibly held projected for a portion of such revolution to travel in the groove of the grinding ring and cooperate with the latter to grind and further 20' reduce the metal, and in which the grinding element is then retracted out of engagement with the grinding ring preparatory to projection again upon the next revolution of the carrier.

Further objects are to utilize the combined forces of gravity, centrifugal force, and fluid pressure to effect projection of the grinding elements for the pounding operation, and to utilize the forces of gravity and suction to effect retraction of the grinding elements.

A still further object is to provide a pulverizing mill of the above type which will rapidly produce a uniformly high grade of metallic powder, which is safe and efllcient in operation, and which is otherwise well adapted to meet with the requirements for a successful commercial use.

Other objects and features of the invention will become apparent from the following description and claims, when considered in connection with the accompanying drawings, in which:-

Figure 1 is a vertical transverse section of a pulverizing mill embodying the present invention.

Figure 2 is a view thereof, partly in side elevation and partly in section. 1 a

Figure 3 is a fragmentary transverse section, illustrating a slight modification of the invention; and

Figure 4 is a view somewhatsimilar to Figure 3, illustrating a further modificationof the invention.

Referring more in detail to the drawings, 5 indicates an upright hollow casing providing a circular pulverizing chamber 6 within which is concentrically arranged a rotatable carrier 7- formed with a circuiar series of radial cylinders 8 having radially movable grinding elements 9 fitted therein. The casing 5 is provided with an internal circumferential groove 10 within which is fitted and secured a stationary grinding ring 11 having an internal circumferential race or groove 12 to receive the material to be ground or pulverized. The grinding elements 9 are arranged to be projected outwardly to the open outer ends of the cylinders 8 where they project partially from the cylinders for engagement with and travel in the groove 12 of grinding ring 11, as will presently become apparent. The cylinders 8 are lined with bearings sleeves 13 to facilitate the radial movement of the grinding elements with minimum resultant wear, and these bearing sleeves are removable for renewal purposes.

Integral with and projecting from opposite sides of the carrier 7 are coaxial stub shafts 14 which are journaled in bearings 15 provided on opposite sides of casing 5 so as to mount the carrier for rotation concentrically of and within the chamber 6. One of the' stub shafts 14 projects outwardly beyond the adjacent bearing 15 for connection with a suitable source of power whereby the carrier 7 may be rotated. As shown, a large spur gear 16 is keyed on this projecting end of this stub shaft, and meshing with said gear 16 is a spur pinion 17 that is secured on the inner end of a power or driven shaft 18. The shaft 18 is journaled in suitable bearings 19 provided at the top of -a bracket 20 bolted at 21 to the adjacent side of casing 5 at the bottom of the latter. Fast and loose pulleys 22 and 23 respectively may be provided on the shaft 18 between the bearings 19 for transmitting power to or discontinuing transmission of power to shaft 18. In other words, a belt may be passed around the power shaft of a rotary motor and around the fast pulley 22 for effecting driving of rotor 7, such belt being slipped from pulley 22 to loose pulley 23 whenever it is desired to discontinue rotation of carrier 7. Obviously, provision may be made for driving the carrier at variable speeds, such as by substituting a cone pulley for the ordinary fast pulley 22 A suitable gear casing 24 may be provided over the pinion 1'7 and gear 16 for safety purposes, which gear casing may be conveniently bolted or otherwise attached to the adjacent side of easing 5. The casing 5 is preferably made of vertical longitudinal half sections having coacting angular flanges at their meeting outer edges to form the groove 10 in which the grinding ring 11 is fitted and secured, said half sections having projecting ears 25. to facilitate bolting of the same together as at 26 and to thereby clamp the grinding ring 11 in place.

An axial bore is provided through the carrier 7 and its stub shafts l4, and fitted in this bore is a shaft having projecting ends engaged in supporting members 26 and 2'7 respectively secured to the hub of gear 16 and to the bearing 15 at the opposite side of the casing. A set screw 28 is carried by supporting member 27 and engages shaft 25 to hold the latter from turning, a lock nut 29 being provided on set screw 28 to prevent accidental loosening of said set screw. A longitudinal passage 30 is provided in one end portion of shat" t 25, and such passage opens downwardly near the center of shaft 25 in communication with a radial port 31. Connected to the outer end of shaft 25 in communication with passage 30 is a pipe 32 leading from a suitable source of fluid under pressure, such as a compressed air storage tank. The pipe 32 preferably has a pressure regulating valve incorporated therein for permitting manual regulation of the pressure of the lluid delivered from passage 30, for a purpose which will presently be described. Another longitudinal passage 33 is provided in the other end portion of shaft 25, and this passage 33 opens at its inner end near the center of shaft 25 upwardly through a port 34. A pipe 35 is connected to the supporting member 27 in communication with the passage 33 and leads to a suitable suction producing means or pump. A radial passage 36 connects each cylinder 8 at its inner end with the bore of carrier '7 and its stub shafts in a vertical plane coincident with the plane of ports 31 and 34, and it will thus be seen that, as the carrier '7 is rotated, the passages 36 will successively register with the port 31 for successively admitting fluid under pressure into the inner ends of cylinders 8 as they approach the lower portion of casing 5, thereby causing the grinding elements 9 to be successively projected downwardly or outwardly of carrier 8 into engagement with grinding ring 11 for pounding and thereby reducing the metal or material to be ground which has been fed into said grinding ring 11. This downward or outward projection of the grinding elements will of course be aided by centrifugal force and gravity due to the downward movement of the grinding elements and the tendency to throw the same outwardly under rotation of the carrier. A very ellicient pounding and reducing action is thus insured, and the degree or fluid pressure utilized may be regulated by a valve in the pipe 32 to suit the nature of the material being pulverized. As

the carrier continues to rotate and the cylinders successively move upwardly, the ports 36 will be successively brought out of registry with port 31 so that the fluid pressure is trapped in the cylinders behind the grinding elements for maintaining them forcibly projected into contact with grinding ring 11. A further rubbing or rolling of the metal is thus caused for a partial revolu tion of the carrier, and as the cylinders successively approach a vertical position near the top of easing 5, the passages 36 will successively register with port 34 to permit the fluid under pressure to be drawn from the cylinders behind the grinding elements so as to insure retraction of the latter to the inner ends of the cylinders as indicated with respect to one of the same in Figures 1 and 2. This cycle of operation will be continuously repeated as long as the machine is kept in operation so that the material or metal being pulverized is repeatedly subjected to the rubbing or grinding and pounding action until reduced to a very fine powder. By creating a suction in the passage 33 and in the inner ends of the cylinders as they approach the top of the casing 5, complete retraction of the grinding elements is insured so that a full stroke of the grinding elements will be insured when they are subsequently projected.

It will be noted that the casing 5 is substantially air-tight with the exception of certain material inlets and outlets. The material to be pulverized is fed into the lower part of the casing 5 through one side thereof where the feed opening or inlet 37 is provided. A depending outlet 38 is provided at the opposite side and near the bottom of easing 5 to facilitate taking samples of the material during the grinding or pulverizing operation. The sampling outlet 38 is provided with a transverse screen 39 so as to only permit the outward passage of powder, and it is understood that the outlet 38 is to be connected with a suitable gate valve whereby the same may be conveniently opened and closed.

The casing 5 is provided at the top and at opposite sides with upwardly extending powder outlets 40 having transverse screens 41 therein whereby the discharge of the material in proper finely powdered form is permitted and discharge of the material in less finely divided form is prevented.

A circular series of radially arranged ribs 42 is provided on each side of the carrier 7 to keep the air within the chamber 6 in circulation when the machine is in operation. These ribs act as fan blades to assist in discharging the powder through the outlets 40, thereby preventing the accumulation of dust and guarding considerably against possible explosions. It has further been found that the fanning effect of the ribs 42 will assist in cooling the interior of the casing to a desirable degree.

The half sections of easing 5 are preferably provided with horizontal bottom flanges 43 which act as a base on which the machine rests, and which may be apertured to facilitate bolting of the machine to a suitable foundation or support.

In the form of the invention shown in Figures 1 and 2, the carrier is provided with a single series of radial cylinders and grinding elements, and such grinding elements are in the form of heavy balls so as to roll when engaged with the grinding 7 ring 11 to minimize wear. However, if a more eihcient grinding action is desired even though greater wear may be involved, grinding elements may be employed in the form shown in Figure 3, consisting of cylindrical plungers having rounded or segmento-spherical outer ends conforming to the race or groove 12 of grinding ring 11. These plunger grinding elements are indicated by the reference numeral 9a, and the machine of Figure 3 will otherwise be similar to that illustrated in Figures 1 and 2.

It will also be apparent that the machine may embody a longer or wider carrier provided with a plurality of series of radial cylinders arranged in side by side relation as shown in Figure 4 to constitute a multiple pulverizing mill. In this figure the carrier is indicated by the numeral 7a, and the cylinders of the respective series are designated respectively 8a, 8b and 8c. The grinding elements in this form of the invention may be either in the nature of balls or plunger-s as suggested respectively in Figures 1 and 3, and the cylinders and grinding elements of the respective series preferably gradually decrease in size from one side of the machine to the other as shown.

In this embodiment, the grinding elements may cooperate with separate grinding rings or with separate grooves in a common grinding ring. Otherwise, the form of the invention shown in Figure 4 will be substantially the same as that shown in Figures 1 and 2, it being of course understood that the shaft 25 in this form will have ports similar to those at 31 and 34 to simultaneously open communication with the passages 36 of the cylinders of the several series. In other words, it will simply be necessary to provide the passages 30 and 33 with additional ports like those at 31 and 34 in Figure 1 for intermittent communication with the passages 36 of each series of cylinders in this multiple form of machine shown in Figure 4.

In operation, the carrier 7 is rotated slowly through the gearing described, and fluid under the desired pressure is admitted from pipe 32 to passage 30. As the carrier rotates, the material to be pulverized is fed into the bottom of easing 5 through inlet 3'? so as to find its way within the lower portion of grinding ring 11. As the grinding elements successively approach the under side of shaft 25, air is admitted into the inner ends of the cylinders so as to forcibly project said grinding elements against the grinding ring 11 to cause a pounding and reduction of the material to be pulverized. In this pounding operation the action of gravity and centrifugal force assists as hereinbefore explained. As rotation of the carrier continues the grinding elements travel along the grinding ring under pressure due to the fluid under pressure confined in the cylinders behind the grinding elements. The grinding elements thus cause a rolling or rubbing action of the metal after pounding the same until they approach the top of the casing 5 where the passages 38 register with port 34 and permit the air to escape. from behind the grinding elements so that they may lower or move inwardly to retracted position at the inner ends of the cylinders. When suction is employed in pipe 35 and passage 33, the retraction of the grinding elements is positively effected even though having a snug fitin the cylinders. The withdrawal of air' from the cylinders insures retention of the grinding elements in retracted position until air under pressure is admitted behind the grinding elements as above explained. It will be further noted that when the grinding elements are projected downwardly, the fluid under pressure behind them acts as a cushion to absorb any shock due to tendency of the grinding elements to rebound upwardly after striking the grinding ring. This cushioning minimizes breakage of parts and thereby assists in insuring long life to the machine although placed in continuous use over a long period of time. It will be seen that the force of pounding effected by projection of the grinding elements may be controlled by controlling the degree of pressure admitted to the cylinders by way of pipe 32 and passage 30. As the pounding and grinding operations continue as explained above, the material fed into the machine will be finely powdered so that it will be easily discharged or blown from the casing through outlets 40 to a suitable point of collection, suchdlscharge being facilitated by the ribs 42 keeping the air within chamber 6 in circulation.

In view of the foregoing it will be seen that I have provided a very simple, efilcient and durable pulverizing mill especially adapted for the manufacture of metallic powder rapidly and of a uniformly high grade. Minor changes in the cular series of radial cylinders, radially movable grinding elements fitted in said cylinders, a fixed grinding ring within the casing surrounding said carrier, fluid pressure means for successively projecting said grinding elements against the grinding ring, and means to automatically relieve pressure from behind the grinding elements to facilitate retraction thereof subsequent to pro- .iection of the same.

2. In a pulverizingmill, a casing, a carrier rotatably mounted in said casing and provided with a circular series of radial cylinders, grinding elements fitted in and movable radially in said cylinders, fluid pressure means to successively forcibly project the grinding elements outwardly at a predetermined point during each revolution of the carrier and to forcibly hold said grinding elements projected for a subsequent portion of such revolution, means to automatically relieve pressure from behind the grinding elements to facilitate retraction of said grinding elements after being so projected, and a grinding ring fixed in the casing in surrounding relation to the carrier and against which the grinding elements are projected and arranged to travel when held projected. I

3. In a pulverizing mill, a casing having a fixed internal grinding ring, a carrier rotatably mounted in the casing and provided with radially movable grinding elements, fluid pressure means for successively forcibly projecting said grinding elements into engagement with the grinding ring as they approach the lower portion of the casing and to hold the grinding elements projected to travel on the grinding ring as they pass upwardly from the lower portion of the casing, and means to automatically exhaust fluid pressure to effect retraction of the grinding elements as they approach the upper portion of the casing.

4. In a pulverizing mill, a casing having a fixed internal grinding ring, a carrier rotatably mounted in the casing and provided with radially movable grinding elements, fluid pressure means for successively forcibly projecting said grinding elements into engagement with the grinding ring as they approach the lower portion of the casing and to hold the grinding elements projected to travel on the grinding ring as they pass upwardly from the lower portion of the casing, and means to automatically exhaust fluid pressure to effect retraction of the grinding elements as they approach the upper portion of the casing, said carrier having radial ribs upon opposite sides thereof to effect circulation of air within the casing during the grinding operation.

5. In a pulverizing mill, a casing having a fixed internal grinding ring, a carrier rotatably mounted in the casing and provided with radially movable grinding elements, fluid pressure means for successively forcibly projecting said grinding elements into engagement with the grinding ring as they approach the lower portion of the casing and to hold the grinding elements projected to travel on the grinding ring as they pass upwardly from the lower portion of the casing, means to automatically exhaust fluid pressure to effect retraction of the grinding elements as they approach the upper portion of the casing, said carrier having radial ribs upon opposite sides thereof to eifect circulation of air within the casing during the grinding operation, said casing having top powder outlets, a bottom inlet at one side for the material to be pulverized, and a screened sampling outlet near the bottom and adjacent the opposite side.

6. In a pulverizing mill, an upright hollow casing providing a circular grinding chamber and provided with bearings at opposite sides, a carrier having coaxial stub shafts journaled in said bearings for rotatably mounting the carrier within the casing chamber, said carrier and stub shafts having an axial bore, said carrier being provided with a circular series of radial cylinders and having passages connecting said bore with the inner ends of said cylinders, a grinding ring fixed in the casing in surrounding relation to the carrier, radially movable grinding elements fitted in said cylinders, a stationary shaft positioned in the bore of the carrier and the stub shafts and provided with fluid pressure supply and exhaust passages respectively opening through said stationary shaft intermediate its ends in a downward and an upward direction and in a vertical plane coincident with the plane of said passages between the bore of the carrier and stub shafts and the cylinders of the carrier, whereby the grinding elements are forcibly projected against the grinding ring as they approach the bottom of the casing, whereby they are forcibly held against and caused to travel in the grinding ring as they move upwardly after projection, and whereby lowering and retraction of the grinding elements is permitted as they approach the upper part of the casing.

'7. In a pulverizing mill, an upright hollow casing providing a circular grinding chamber and provided with bearings at opposite sides, a carrier having coaxial stub shafts journaled in said bearings for rotatably mounting the carrier within the casing chamber, said carrier and stub shafts having an axial bore, said carrier being provided with a circular series of radial cylinders and having passages connecting said bore with the inner ends of said cylinders, a grinding ring fixed in the casing in surrounding relation to the carrier, radially movable grinding ,elements fitted in said cylinders, a stationary shaft positioned in the bore of the carrier and the stub shafts and provided with fluid pressure supply and exhaust passages respectively opening' through said; stationary shaft intermediate its ends in a downward and an upward direction and in a vertical plane coincident with the plane of said passages between the bore of the carrier and stub shafts and the cylinders of the carrier, whereby the grinding elements are forcibly projected against the grinding ring as they approach the bottom of the casing, whereby they are forcibly held against and caused to travel in the grinding ring as they .move upwardly after projection, and whereby lowering and retraction of the grinding elements is permitted as they approach the upper part of the casing, and a suction pipe communicating with said exhaust passage to forcibly retract the grinding element.

8. In a pulverizing mill, an upright hollow casing providing a circular grinding chamber and provided with bearings at opposite sides, a carrier having coaxial stub shafts journaled in said bearings for rotatably mounting the carrier within the casing chamber, said carrier and stub shafts having an axial bore, said carrier being provided with a circular series of radial cylinders and having passages connecting said bore with the inner ends of said cylinders, a grinding ring fixed in the casing in surrounding relation to the carrier, radially movable grinding elements fitted in said cylinders, a stationary shaft positioned in the bore of the carrier and the stub shafts and provided with fluid pressure supply and exhaust passages respectively opening through said stationary shaft intermediate its ends in av downward and an upward direction and in a vertical plane coincident with the plane of said passages between the bore of the carrier and stub shafts and the cylinders of the carrier, whereby the grinding elements are forcibly projected against the grinding ring as they approach the bottom of the casing, whereby they are forcibly held against and caused to travel in the grinding ring as they move upwardly after projection, and whereby lowering and retraction of the grinding elements is permitted as they approach the upper 'part of the casing, a suction pipe communicating with said exhaust passage to forcibly retract the grinding element, and removable bearing sleeves fitted in said cylinders.

OTTO DA COSTA SCHMIDT. 

